Ask Ian Axel and Chad Vaccarino of A Great Big World the inspiration behind their mega-hit, “Say Something,” and the answer is simple: “We were both heartbroken,” Axel tells Parade.com.

Heartbreak has led to a top-charting song, a collaboration with pop goddess Christina Aguilera, and a performance at the Victoria’s Secret Fashion Show — all in the span of a few months.

The music duo, who met while studying music business at NYU, talked to Parade.com about their whirlwind year, their new album, and more.

How have you handled sudden success?Chad Vaccarino: “We’ve had the most mind-blowing experiences of our lives over the last two months. After the Christina Aguilera collaboration and being on The Voice, it felt like our lives changed forever.”Ian Axel: “It’s been a little hard because we’ve never dealt with this before, especially with the traveling. It’s been a major adjustment. Not having a routine is the hardest thing for me.”

What was it like working with Christina Aguilera?Ian: What surprised us was how respectful she was of our song. We suggested she take a verse on it and sing out and belt all over it, but she just wanted to sing harmony. We were floored by that — it’s the biggest compliment. She sang so sensitively and so vulnerably.”

What’s the inspiration behind the song?Ian: We were both heartbroken at the same time, and on top of that, we were not happy. We were working jobs that we wanted to get out of. We had been writing together for eight years, but during that time, we took a year off from writing because our spirits were down, and ‘Say Something’ was one of the only songs we wrote during that period. It was our therapy and helped us get through it.”Chad: “Through the process of writing that song, we found closure from these toxic relationships we had going on.”

What’s your writing process?Ian: “It’s different for every song. But for ‘Say Something,’ I think it was Chad who had an idea on guitar and I had an idea on piano for different songs and we just married them together. We bounce things off each other constantly and kind of massage all these ideas into a three and a half minute pop song.”

When you wrote “Say Something,” did you know you had a hit on your hands? Ian: “We were definitely in the most honest place we’ve ever been with ourselves and it really felt like we dug deep. It was the first time writing felt like a religious experience for me. It was so painful, but also so beautiful. It was very powerful and moving for us to write it, but we never thought it would take off like this.”

What can you share about your new album? [Is There Anybody Out There? will be released on Jan. 21.]Chad: “You’re not going to get 13 ‘Say Somethings.’ You’re going to get a huge spectrum of emotion. A lot of it is fun, upbeat pop music.”Ian: “Each song was significant to us at the time we wrote it. It’s like bookmarks for different chapters in our lives.”

How did you come up with your band name? Chad: “There’s a song on the album called ‘Cheer Up’ and a lyric in there that goes: ‘It’s a great big world and there’s no need to cry,’ so it comes directly from that song. We just felt like it was super optimistic and hopeful. It’s big and it really fits into what we’re about.”Ian: “Yeah. The fact that we’re all connected and we’re all in this thing together. It’s a great big world, but at the same time, it’s really not that big, and the whole reason we’re putting out this music is to connect with people. That’s part of the human occasion.”

You had a very memorable performance at the Victoria’s Secret Fashion Show last month. What was that like? Ian: “It was a lot of fun and something we’ve never experienced before. It was surreal to perform alongside Taylor Swift and Fall Out Boy. We’re huge fans and they were so nice. It was just a very fun atmosphere to be in, and we loved how theatrical it was, we’re all about that. It was interesting playing ‘Say Something’ while all these beautiful girls walked past me!”

What was the last song you downloaded? Chad: “I downloaded Tessanne Chin [Season 5 Voice winner] singing ‘I Have Nothing.’ Her voice is so amazing. It’s so ridiculous.”Ian: “My last one was Jon Secada’s ‘Just another Day’ because I was in that mood. And then ‘My Friends’ from Red Hot Chili Peppers and John Legend’s ‘All of Me.’”

What’s in store for the year ahead? Chad: “We are looking to hopefully tour the world in 2014 and 2015.”Ian: “And 2016!”Chad: “Yeah. And we’re going to release this album and also Ian and I are working on a Broadway musical and we’re looking to finish that up this year. Two Broadway producers and a book writer who wanted pop music for their musical approached us. The musical we’re writing is kind of our music on steroids!”

Watch A Great Big World and Christina Aguilera perform “Say Something” on The Voice: